Signal apparatus



April 30, 1935. 5 BEAH 1,999,859

S IGNAL APPARATU S Filed Nov. 5. 1931 8 Sheds-Sheet l 5 51 j INVENTOR-ATTORNEY CZ. E. BEACH SIGNAL APPARATUS April 30, 1935.

INVENTOR ATTORNEY A ril 30, 1935. -c E. BEACH 1,999,859

S IGNAL APPARATU 5 Filed Nov. 5, 1951 s sheets-sheet s INVENTOR ATTORNEY'c. E. BEAC lH SIGNAL APPARATUS April 30, 1935.

Filed Nov. 5, 19 l 8 Sheets-Sheet J6 a 6hr 673629 fine)? April 30, 1935.-c. E. BEACH SIGNAL APPARATUS Filed Nov. 5, 1931 8 Sheets-Sheet 6 A ril30, 1935.

c. E. BEACH SIGNAL APPARATUS Filed Nov. 5, 1931 8 Sheets-Sheet 7 April30, 1935. 'c. .EfBEACH SIGNAL APPARATUS Filed Nov. 5; 1951 s Sheets-Sheet 8 fiiaferal07 hrer 1 592; 5.9%

?aten ted Apr. 30, 1935 PATEN OFFICE 1,999,859 v p SIGNAL APPARATUSClarence E. Beach, *Brookline, Mass., assignor to The Gamewell Company,Newton Upper Falls, Mass, a corporation of Massachusetts ApplicationNovember 5, 1931, Serial No. 573,150

44 Claims.

This inventionrelates to signal formulating *or transmitting mechanismsand systems, and more particularly to improvements in apparatus of thetype comprising a. series of widely separated signal transmittersconnected to a central signal receiving station, for example, toapparatus such as a circuit including a plurality of fire alarm boxes orsimilar signal transmitters connected to a central signal receivingstation. The invention particularly aifords improvements in successivenon-interfering signal transmitters as commonly employed for suchpurposes.

Apparatus of the class to which this invention relates is dependedupon-to avoid serious property lossand even inmany cases loss of lifeitself; accordingly, it is a primary object of the present invention toaiford an especially dependable signaling apparatus and particularly toprovide a device of this character which is operable under a widervariety of adverse conditions than has been the case with any device ofthe general character which has been heretofore provided. Particularlythe present invention provides a signaling device adapted to transmitsignals over an emergencyline or common return, suchasa ground, if theregular circuit becomes faulty, while-avoiding the closing of such anemergency circuit whenthe normal operating circuit remains. properlyconditioned. This invention also afiords a signaling device'arranged tooperate when serially associated with similar devices withoutinterference between such devices even if they are simultaneously orsubstan-- tially simultaneously actuated. Thus the present inventionafl'ords an improved type of signaling device of the perfectnon-interfering type, as

well as a device having animproved emergencyswitch or ground wirereturnarrangement, and this invention particularly provides for the con-.venient associationof both of these advantaof code signal transmittingcall or alarm boxes,

and in which, at a central point or station, the

loop ends are connected through indicating or control devices to asuitable current source. Such, current sources are generally referred toas the central station battery and may be normally free from groundconnections so that the faults may develop or threaten in'the circuitsor apparatus, so that intended signaling response at the central stationmay result. from closing and breaking of a connection between. one orthe other or both portions ofthe signal circuit and the event that thenon-interference magnet or its associated parts become disabled. Thefunotion and purposes of this magnet and its related parts then beingautomatically dispensed with during emergency signaling operations. Topermit these desirable results, test operations may be carried out insuch a manner as to differentiate between a busy condition of thecircuit and a malcondition thereof. Furthermore, should the testingoperation indicate a malcondition of the circuit, the mechanism is soarranged that it will stop operation after the elapse of acomparativelyshort interval, thus conserving the energy stored within the motorspring and preventing needless exhaustion thereof, so that the motor maybe ready to operate in response 1; a subsequent pulling of the box.

It is still another object of this invention, when the test operationsshall point to a busy condition of the circuit, to provide that effectsshall transpire progressively to limit the number of times a finallysuccessful waiting or seeking box may repeat its signal. Theserestrictions vary inversely as the length of the preceding busy period:

for a firstlength of busy period one repetition of a signal shall bedeleted; after a slightly longer busy period two repetitions of thesignal are deleted; proceeding in like manner, such eii'ects maycontinue until a transmitter may send its signal but once, withoutanyrepetition; and, finally, should the length of the busy period extendbe yond a second predetermined time limit, the mechanism of the waitingsignal box abandons its attempts to seize the circuit and-restores itsmechanism to normal, while still retaining enough energy stored in itsmotor spring for carrying out any subsequent signaling as may berequired. in .the regular eventuations of the service.

- A further aspect of this invention relates to the arrangement of themechanism so that the complete signal may ordinarily be transmitted,even when the current supply is abnormally low, if thereis'sufiicientcurrent to permit initial seizure of the linejby thetransmitter. Accordingly certain objections which have characterizedprevious mechanisms of this general type are avoided, since there islittle possibility of the transmitter taking possession of the line andsending an incomplete or mutilated code signal, thus giving a .false orwrong alarm indication.

More particularly objects of the invention are: To render thenon-interference and succession mechanism ineflective in the event offaflure of this mechanism to be influenced, by adequate energization ofthe electromagnet, for a time longer than the longest interval betweenmagnet energizations which should occur incident .to the formulation ofany signal, to the end that the mechanism may act without thenon-interference and succession functions to effect the formulation ofthe intended code signal notwithstanding any defect or disablement towhich the non-interference magnet or its associated mechanism may besubjected; to short-circuit the winding of an busy circuit, withouthaving caused effective response to its signal formulation,

In the drawings: I

Fig. 1 is a front elevational view of improved transmitting apparatusconstructed in accordance with the present invention, certain partsbeing broken away for clarityof illustration;

Fig. 2 is an isometric viewof a portion of the assembly shown in Fig. 1,parts being broken away and removed to show clearly the arrange-. mentof the electrical conducting elements and related parts;

Fig. 3 is a side elevational view of a portion of the assembly shown in1, certain partsbeing removed;

Fig. 4 is a front elevational view of certain portions of the signalingapparatus, including pormoved and the position of the remaining partsbeing that which they occupy during a signal transmitting period; i

Fig. 6 is a rear elevational view of a portion of electromagnet includedin an intended signaling assembly; particularly showing a part of thesigpath in the event of the failure of such magnet to become effectivelyenergized throughout a time longer than the longest intendednon-energization interval incident to the formulation of any signal, tothe end that in the event of rupture of the.current path through anysuch m et winding, the intended code signal may nevertheless betransmitted over the'normal metallic circuit, irrespective of theeffectiveness of any ground or emergency circuit connection; to providean emergency common return or ground connection only following theexpiration of a time. measured by the rlmning of the train during whichthe magnet remains deenergized, which time is longer than the longestintended nonenergization period incident to the formulation of anysignal, and, at the same time, establish one ormore of the otheremergency conditions ,iust

referred to; to assure effective signal formulation in the normalcurrent path, irrespective of eifectiveness of any ground connections,notwithstanding any degree of impairment of the normal line ,,,currentstrength; to provide -a non -interference mechanisms now known, so longas the normal signaling current path remains unimpaired; to effectconservation of the main spring or other driving power for thetransmitter mechanism by provision of means whereby, if the mechanism isnal train .and the escapement mechanism associated therewith;

Fig. 7 is a front elevational view of the signal wheel;

Figs. 8 and 9 are edge views of the same, showing the relationship ofthe wheel to a portion of the sender arm;

Figs. 10 and 11 are elevational views-of certain parts of the apparatus,showing the position of the same when the signal train is stopped andFigs. 15 and 16 are 'iront elevational views of thesignal wheel, senderarm and the related electrical contact and conductor assembly:

Figs. 17, 18 and 19 are front elevational views of a portion ofthe stoptrain mechanism and related parts, showing these parts under variousoperating conditions; Fig. 20 is an isometric viewof the master plateassembly; and 1 Figs. 21, 22 and 23 are typical wiring diagrams. For thepurpose of facilitating comprehension of this invention and illustratinga manner or applying the several improvements thereof to a type ofmechanism with which those skilled in this art are familiar, theembodiment of this invention shown by the accompanyingdrawings andhereinafter described in detail is one utilizing portions of mechanismsuch as that of the successive non-interference signal box disclosed inUnited States Letters Patent to Frederick W. Cole, No. 1,244,587, issuedOctober 30, 1917. Portions of such mechanism which are clearlyillustrated and described in said Cole-patent are not always hereindescribed in detail, except in in-- Motor and signal train The motormeans and a portion of the signal .train may be similar to thatdisclosed in the above-identified prior Cole patent, as shown in Fig. 1,the outer end of main spring I is fixed to a stud 2 anchored to theouter frame plate 3 of the assembly, the inner end of this spring beingattached to the main shaft 4 (Fig. 3). The ends of shaft 4 are journaledin front and rear plates 3 and 3*, these plates being held in spacedrelation by struts Ill. The winding handle 8 may be turnedcounterclockwise, as viewed in Fig. 1, to

wind the spring I to condition it for imparting a clockwise movement toshaft 4 when the spring is released. A gear I cooperates with a rotatingpinion 3 and carries a stop pin I2 for engagement with an arm |4 movingwithsaid pinion to prevent overwinding in the manner described in theabove-identified patent.

A ratchet wheel 5 secured to shaft 4 engages a spring-pressed pawl 6that is pivotally mounted on a spur gear 1 free to rotate on shaft 4(Fig. 6). The gear wheel 1 meshes with a relatively small pinion IS onthe shaft l1, which carries the signal wheel l8 (Figs. 1 and 3) A gearwheel 19 secured to shaft |1 meshes with a pinion 2| fixed to shaft 22and to the escapement wheel 23. The latter engages a speed limitingpallet 24. (Fig. 6) mounted on a pivot 26, arms 21 and 28 extending fromthis pallet and bearing respective adjustableweights 3| and 32 to affectthe speed of the signal train and thus control the speed of the signalwheel I 8.

Manual control A lever 33 is-disposed in front of the, frame plate 3 andconnected to a pivot shaft 34, the latter carryinga projection 3B-Whichhas a camlike engagement with a rocking or master plate 31 to swing thelatter clockwise (Figs. 1 and 5). Plate 31 is mounted on a pivot 38(Fig. 20) that is rotatably mounted between the front and rear plates 3and 3, while an arm I62 moves with said shaft 38 and has a hookedprojection 'engaging the end of retractile spring 52, the opposite endof which is connected to a pin projecting from plate 3. Plate 31 isdisposed directly behind plate 3 and has an extension affording a tracerarm 39 (Figs. 10 and 11), which may ride the dished periphery of orenter a notch 42 in a rounds measuring disk 4| that is rotatable on butindependently of main shaft 4. A stop dog 40 has a pivotal connection 43with the plate 31 and is simultaneously shiftable from engagement withthe stop pin 44 projecting from gear wheel l9 when the tracer arm 39 iswithdrawn from the notch 42, to permit the signal train to startoperation under the action of main spring I. When the arm 39 of themaster plate moves into the notch 42 of the rounds measuring disk 4|,the

stop dog 40 is brought into the .path of the pin 44 upon the wheel l9 toarrest and retain the mechanism in its inoperative position. When thenotch 42 has moved out of registration with the arm 39, the tensionspring 52 presses the end of said arm against the flanged periphery ofthe measuring disk 4|, thus retaining the master plate in its operativeor clockwise position and affording brake means for the disk to preventoverrunning thereof.

The stop dog 40 is substantially in the form of a bell crank and has anarm 4|) with a bifurcatedend looselyen'gaging the escapement-wheel shaft22. The dog also has a slotted bearing portion 40 engaging the pivotstud 43that .projects from plate 31, and cooperating with a coil spring53 which is looped about a boss concentric with the pin 43. Thisarrangement affords a clearance between walls of the slot at the end ofarm 40 and the shaft 22 and permits the end of dog 40 to snap away fromthe pin 44 with a positive and rapid movement; thus preventingreengagement of the end of stop dog 40 with pin 44 and assuring positiverelease of the train irrespective of how quickly the pull handle isreleased after pulling.

The use of the stop pin 44 upon the gear H3 is particularlyadvantageous, since the strain from the spring I received by the pin,the dog40 and the related parts is comparatively low due to the gearratio between gears 1 and I6 and the shafts Signal wheel assembly Thesignal wheel |8 may be detachably secured by a. set screw 20 to theouter end of shaft 1, thus to permit ready interchangeability (Fig. 5)and is provided with a plurality of teeth 30 in accordance with thedistinctive code signal that is to be sent from the individual box. Thesender arm or automatic key 9| is pivotally mounted upon the front plate3, as indicated by numeral 52, and is provided with a lug or fluke 93(Figs. 15 and 16) which is engageable with the protuberances 30 on thesignal wheel. Aninsulating block or abutment 34 secured to arm 9|engages the twin contact springs 61 and 68 (Fig. 2), therebyto set uppulsations in electrical current, as will presently be described, whilethese springs yieldably urge arm 9| toward wheel l8.

A member 96 depends from the lower end of the sender arm 9| and normallyabuts a stud 91 (Fig. 1) projecting from master plate 31, so that thelatter in its normal position holds the lever 9| andfluke 93 out ofengagement with the a peripheral portion of the wheel I8. The end ofthis skirt has an advanced, inclined corner portion IOI. When the masterplate 31 initially moves out of its normahp osition 'to release the arm9|, the edge of skirt I00 engages the fluke 93 and holds the latterspaced from the periphery of the signal wheel I8, while the'contacts ofassembly PC remain in engagement under the action of their supportingsprings. As shown, the

wheel I8 is provided with a continuously curved,

void or interdental space adjoining the skirt. After the wheel I8 isrotated so that the skirt I00 no longer is disposed adjoining the fluke93, arm 9I may, under certain conditions, swing toward the wheel, sothat, during subsequent revolutions, thelip or inclined corner IOI ofthe skirt may engage the fluke with a cam-like action, the shield thusbeing stressed and engaging the inner face rather than the edge of thefluke (Fig. 8), thus permitting said skirt I00 to be rotated past saidfluke without'thereby either lifting or supporting said arm 9I.

Electrical connections Referring first to the typical wiring diagram ofFig. 21, it is to be understood that a plurality of boxes or instrumentsC, D, E, F and G, such as disclosed and described herein, are arrangedin series, the parts of the box E being shown diagrammatically. Theboxes, as thus connected, are joined by main leads B and H to therespective sides of a central'battery CB, the lead B operating asignal-responsive or recording device A at one side of the battery andthe lead H similarly operating a device J. The emergency working switchEW, as shown in Figs. 21 and 23, has a contact K connecting the linesection H with the left end or minus terminal of the-battery; but isadjustable (Fig. 23) so that the ground connection or common return CRmay be connected to this terminal of the battery by the engagement ofelements L and K, while the conductors H and B are then connectedthrough element M with the opposite battery terminal.

' The devices A and J may be capable of transferring signals receivedfrom the outlying boxes in any well-known or desired manner, as byvisual, audible, recorded or any suitable combination of such forms ofsignal manifestation.

Fig. 2 illustrates more particularly the connection of the externalleads to the individual signal transmitting apparatus and also thearrangement of electrically conductive components of the apparatus. Theterminal 56 may be connected to anexterior line section, such as thesection B, while a similar terminal 51 is connected to the opposite linesection, as thesection H. A third line secto the upper part of thehorizontal leg of this angle. Angular contact springs 61 and 68 aresecured by terminal post bars H and 12 against the lower surface of thishorizontal leg of the manner.

site leg yieldably presses against the first leg, as well as providing askirt I00 extending beyond insulating angle 66. The springs 61 and 68are arranged so that their depending legs, which follow arm 9| aspreviously described, also provide contacts normally engaging similarcontacts at the lower ends of springs 62 and 64, respectively, (seeFigs. 2 and 15), while the horizontal legs of springs-61 and 68 areturried'up to provide contacts 13 and 16 of the emergency switchassembly, indicated generically by reference characters ES. A springmember 11 is clamped to the block 66 by the terminal member 58 to 'serveas a third contact element of the switch ES, Figs. 1 and 2.

Secured to the master plate 31, a block of insulating material 19carries a return bent resilient member 8|, the free end of which isbifurcated to form two contact springs 82and 83, normally to engage therespective contact members 6| and 63. The member 8I forms a shuntingconductor, and since it is movable with the master plate 31, it normallyengages the contactors 6I- and 63, thus joining theline terminals 56 and51 and shunting out the circuits of the transmitter unit. In a conversemanner, when the master plate 31 is, rocked clockwise, the member 8|will be retracted from the line-springs 6| and 63, thereby removing theshunt from the transmitter. This switch is commonly referred to as thebox-shunt", and as its actuation occurs only in the .operation to effectan ofi-normal condition of the transmitter mechanism, it will beindicated by the appropriate functional reference characters ON;

On removal of the box shunt as just described, a path may be traced fromline terminal 56 over the normally engaged contact springs 62 and 61,terminal post bar 1|, conductor 86 to the two serially connected magnetcoils 86, of a master magnet MM, thence over a conductor 81, terminalbar 12, and the other set of normally engaged contacts provided bysprings 68 and 66, to the other line terminal 51. Thus, the first twoline circuit sections may be joined, at certain times, through themagnet MM in completing a loop circuit, the current in which causes themagnet to attract its armature 88, and thereby "initially condition thetransmitter to operate in a standard or normal The non-interferencemagne MM serves divers major functions and is of universal utility inthe present mechanism; accordingly, it

. may also be referred to by this functional term,

master magnet.

Sender arm control assembly The armature 88 normally is drawn away fromthe magnet MM by a spring I I2 and has integral levers I02 and I03rocking about a pivot element I04 (Figs. 5 and 11), one of the struts I0acting as a stop to limit the movement of the armature under the tensionof spring II2 (Fig. 1). The lever I02 is movable into and out of thepath of a guard pin I06 which extends rearwardly from the upper end ofsender arm 9I and which has a fiat surface adjoining the end of arm I02.The lower end of lever I03 provides an outturned ledge I01 movable intothe path of a swinging pawl I08 pivoted at II9 (Fig. 13) on theleft-hand end, as seen in Figs. 5, 11 and 12, of a latch member I09.When the current flowing to magnet MM is uninterrupted as the signaltrain starts operation, the ledge I01 is disposed below pawl I08 and thepawl may rest thereon, so that the right-hand end of the latch member isheld beneath the path of guard pin I06, despite the tension of springI28 connecting this end of the latch with the plate 8 (Figs. 5 and 12).Thus, when the armature is pin may be cleared so that sender arm 9| canreciprocate.

The contacts provided by springs 62 and 64 remain in engagement with thesender contacts provided by springs 81 and 68 for an intervalsufiiciently long vafter the sender 'arm 9| has started. its movementtoward the left in beginning. an impulse formulatiomto permit the guardpin I06 upon arm 9| to pass beneath the righthand end of lever I02before separation of the contacts occurs. Accordingly, when thesecontacts separate and effect deenergization of magnet MM, the lowersurface of lever I02 rides .upon the upper surface of pin I06 throughthe remainder of the sender arm stroke toward the left and the returnportion of this stroke (Fig. 16) until the contacts of switch PC haveagain moved into mutual engagement. Thereupon reenergization of magnetMM takes place so that the armature 88 is electrically retained in itsportative position. While the armature 86 is thus continually held inits attracted position, the free end of the lever I02 is withdrawn fromthe path of guard pin I06, and if the latch I09 has previously beenwithdrawn from the path of said pin I06, it will be held out of suchpath by the engagement of the lower end of the pawl |08Qwith the ledgeI'I carried by the arm I03. The sender arm will therefore be free tooperate in response to rotation of the signal wheel I8 so long as thepositions of the parts just referred to remain unchanged.

Normally the actuating cam H3 is at rest be- I neath the projection I21of lever I09 to prop the latter against the tension of rotator springI28 (Fig. 12). Slight advance only of the signaling train from normal issufficient to move cam 3 beyond fluke I21, so that unless otherwisestayed (as by engagement of pawl I08 with ledge I01 when armature 88 isin its portative position), the member I09 may swing to its blockingposition,

where its right end is in the path of guard 'pin I66 and whereit'encounters the stop pin I34 fixed to the frame plate 3 (Fig. 13). Inthis position the left-hand end of member I09 supports the depending endof pawl I08 in the path of the intersecting extension I01 of lever I03,and also in the path of the angle I24 at the end of restoring lever I22.A pawl-I I4 pivoted at IIS on plate 3 is engageable by the cam II3. an:instant after it starts rotation, so that when the latch lever I09 isin its blocking position the pawl is lifted and its projection I I'Iisseated or latched on a ledge I I8 (Fig. 14) of the latch pawl I 08, asshown in Fig. 13. The retractile spring continually tends to swing pawlII4 counterclockwise on pivot 6, so

that it tends to project into the path of the actuating cam I3, whilethe tension spring I26 connects an ear on member I08 with the pivot pinI 2|, that supports latch I09, thus yieldably swinging the upper portionof member I08 toward the projection II! and toward or against a sleeveon armature pivot I04, which acts as a stop.

In order to permit the latching just described,

the dual purpose stud 91 of the master plate 31 projects between theextremes of the bifurcat ed end of the latch restoring lever I22 (Figs.5 and' 13) pivoted to the frame plate 3 at I23 and serves, in theoff-normal position of the plate 31, to rock the lever I22, swinging itsupper or free end to the left, so that an angle I24 thereon may bewithdrawn from its normal abutment against the lower end of the pawlmember I08 (Figs. 1, 5, 12 and 13). This permits the spring I26 to swingthe upper end of the member I08 to the right for latching the liftedswitch pawl II4, as just described.

When the armature 88 is rocked on the pivot |04-due to momentaryenergization of magnet MM, the projection I0'I of the lever I03 moves totheright against the depending end of the latch I08 to eifectcounterclockwise movement of the latter member, thereby withdrawing thelatch-ledge 8 from the keeper I I! of the switch actuating pawl 4. Thisaction completes the cycle of busy test operations for the first roundof the signaling wheel I8, and in these operations the ground switchactuator H4 is lifted and latched in an intermediate position andsubsequently released to return to normal positionin preparation formeeting other than a busy condition on the line. Description of thelatter efiects will presently be continued.

The unlatching of the switch actuator I I4 at this time merely indicatesthat the only non-)normal condition of the line circuit found to bepresent the path of the guard pin I06 to keep the sender arm 9|ineffective during the remainder; of this first round.

The busy test operation just described will be repeated at the beginningof each round of the signal wheel I 8, asthe signaling train continuesto run, and constitutes successively repeated attempts of the-presenttransmitter to' seize the. circuit for immediate use. At the end of eachround, the cam I I3, in-passing under the tracer I 21 of the sender lockI09, rocks the latter clockwise momentarily to remove the righthand endof this member from the path of the guard pin I06, in presenting thesender arm 9| for possible control acceptance by the signal wheel I8.The completion of the round or cycle of the signal wheel occurs at "atime when the shield 98 supports (as will be hereinafter more fullyexplained), on its edge, the tracer 93 of the arm 9| to prevent movementof said am toward wheel I8, and since the first round was ineffective tosend on account of the busy condition assumed as having beenencountered, the lever I09 continues to prop the sender arm 9| in itsineffective position until entire completion of the round. At the latterinstant, the shield 90 is again in the position in which it is shownin'Fig. 1, where its skirt I00 supports arm 9| while lever I09 is beingwithdrawn from the path of the guard pin I06. Therefore, under thecontinuing operation of the signaling train and at the beginning of thesecond round of the signal wheel I8, the various parts concerned in thetesting operations will be in the same posi-' tions in which they wereat the beginning of thefirst or initial round.

The edge of shield I00 has a slightly eccentric [contour at I0 I, sothat the advance portion thereof may engage the fluke 93 with a cam-likeac-'= tion, moving the pin I06 slightly to the right out of engagementwith latch I09, so that the latter may freely move under the action ofcam 3 to its non-blocking position. The pin|06 and arm 9| may occupy anyone of five posi- .tions: first, the normal position wherein pin 91engages tailpiece 96 and the fiuke 93 is slightly spaced from shield 98(Fig. 1) second, the position wherein the fluke 93 rides on the edge ofthe shield (Fig. 15); third, the position wherein the pin I06 engagesthe end of arm I09 (Fig. 13); fourth, the position wherein the flukeengages the top of a tooth of wheel I8; and, fifth, the position whereinthe fluke engages an interdental surface of wheel I8. In the first fourpositions the contacts of assembly PC may remain closed; in the lastposition thecontacts are separated.

Ground switch control When the armature arm I02 and the latch I09 aredisposed in the path of pin I06 due to the armature being in its raisedposition, the cam II3 may engage the projection I21 and thus rock themember I09 clockwise. The upper surface of the projection III of switchactuator I, if it has remained in its lifted and latched position on theledge H8 of member I08, will then be elevated to its'actuating positionagainst the lower edge of a projection I36 on a switch latch lever I31pivotally mounted on frame plates 3 and 3", as indicated by numeral I38(Fig. 11). The elevation of the left-hand end of member I09 then thruststhe extension III against projection I36 to rock lever I3Icounterclockwise. Thus, the switch actuator I ll is lifted in two steps,the first resulting in the latching on ledge II8 (from which it isdislodged if magnet MM is momentarily energized to swing part I'Iagainst pawl I08), the second step occurring after substantially onerevolution of cam II3 following the first step and involving theengagement of the cam II 3 with the fluke of latch I09 while the memberII l is supported by ledge II8. Ac-

cordingly, the movement of actuator I to rock lever 131 will only occurif the magnet MM has remained deenergized during substantially onerevolution 'ofthe shaft II. The upper end of lever I 31 is curved toprovide a keeper for retaining cylindrical contactor or switch member I8in its ineffective position, as shown in Fig. 12. The counterclockwisemovement of lever I31 accordingly releases contactor I8 and a projectionI39 on the lever engages a protuberance I l0 from the armature 88,mechanically rocking the armature into its portative position (Figs. and11) The contactor I8 is secured to the end of a lever IlI, a tensilespring I 42 tending to move this lever clockwise about the' pivot l3carried on master plate 31 (Fig. 5) to thrust contactor I8 intoengagement with .contact springs I3, H

The free end of lever I 31 has an inclined end engaging the contactorI8, such end being so formed that during movement of the arm Iresponsive to spring 2, as the contactor I8 passes along said inclinedsurface it will cause the arm I3I to swing somewhat in acounterclockwise direction and thereby act through the extension I39moving with said lever I31 and the flexible strip 0 associated with thearmature 88, to firmly hold said armature and its associated assembly inportative position and, at the same time, to stabilize contactor I8 inengagement with the contact springs I3, ll and 11. While the armatureassembly is thus maintained in its portative position, the ledge I 01carried by the lever I03 is disposed in the path of the lower end of thepawl I08 and thereby prevents the descent of the latch lever I09 attimes when the support of the cam I I3 is withdrawn from the projectionI21 of said latch lever; with the result that neither the free end ofsaid latch lever I09 nor that of the arm I02 will be disposed in thepath of the pin I06, and the arm 9| will be free to move in response tothe rotation of the signal wheel.

Stop train and related control mechanism A pawl cam l6 fixed to signalgear shaft IT has a notch l5 engageable with a pawl l8 that is pivotallymounted on a rotatable member lI in loose assembly with the shaft, II(Figs.- 5 and 14). A spring 50 engages the pawl l8 and thus tends toretain the opposite end of the latter in engagement with the recess l5,to hold the clutch in its closed or operative position, so that themembers l6 and H may be caused to rotate as a unit with the signal wheelshaft I1 and the members fixed thereto. Member l'I carries a gear lIwhich meshes with a wheel 5I amxed to the measuring disk lI upon themain shaft l (Fig. 3). When the clutch l6-l8 is closed, the signal andstop trains operate together to bring the rounds disk H to its normalposition sothat spring 52 (Figs. 5 and will rock plate 31, and cause arm39 to reengage the notch l2, and the stop dog l0 to engage the stop pinll.

The signal and stop trains preferably have such a gear ratio that themeasuring disk lI normally makes one revolution during four revolutionsof the signal wheel I8. Under certain conditions, however, the clutchl6- l8 is open so that the signal train continues in motion while themovement of the stop train is interrupted.

Accordingly the signal wheel may continue rotating and tests of thecircuit conditions may be made through the armature and latch mechanism,while the rounds or measuring disk lI remains stationary at one point ofits path.

A skipping dog I29 (Figs. 4 and 14) loosely swung on the pivot shaft I0lis continuously stressed clockwise by a rotor spring I3I extending fromthe dog about a boss concentric with shaft IN and having its remote endconnected to a pin upon the armature lever I02. An arm I32 projectsforwardly from dog I29 to engage a sloping extension or fluke I33 on theupper edge of the left-hand end of latch lever I09, so that the lowerextremity of dog I 29 may swing downwardly to engage the pawl l8 whenthe right-hand extremity of the latch lever is raised 1 to its blockingposition. Accordingly, the lower end of the skipping dog I 29 is thendisposed in the path of the pawl 48 so that it may engage the pawl afterthe shaft I I has made substantially onerevolution, thus to disconnectthe clutch elements 46 and 48 and cause cessation ofmovemerit of themembers 41, lI upon the shaft l1, and of the measuring disk M and itsgear 5! upon the main shaft l, the end of stop arm 39' engaging thedished periphery of the measuring disk under these conditions to act asa brake and prevent accidental forward movement of the same as theclutch is held out.

-wheel I52 at cessive advancing steps thereof, both of the shoulders I66and I61 of the holding pawl incidentally purpose, the stepping and I 9may engage ratchet teeth on a counting wheel I52 that is loosely mountedon main shaft 4, advancing this wheel one step (Fig. 17) under thecontrol of a click element I53 and against the tension of a spring I54which is adapted tobe wound on a grooved hub I56 on the counting wheel.Spring I54 is secured to the element I53 and to a stepping pawl I51pivoted to ratchet I58, this spring serving the triple purpose ofdrawing the ratchet wheel to its normal position, yieldingly retainingthe pawl I51 against a stop pin I59 on the sideof the ratchet wheel andstressing the holding pawl or click element may engage teeth of thecounting wheel I52. The

engaging the end of the retractile spring 52 for plate 31.

An aperture I BI in the body of the pawl I 53 receives the angledextremity I63 of the arm gage the teeth of the counting ratchet wheelI52,

will then be retained by engagement of the end of the pawl I53 with thelong I64. During the second round of the mechanism, the pin 44 engagesthe next lower or eleventh tooth of the counting ratchet I52 inadvancing it a second step, whereupon it is retained by engagement ofits last tooth I 69v with the last ledge I61 or the holding pawl I53,

may dually engage teeth ing wheel as advanc operate in holding it onsucceeding steps,

which its of the tracer 39.

and

of advancing the disk notch 42 will be inretaining the counted (Fig.18).

presented in the path The interdental space between the long tooth I641y ride the point of t to the stepping pawl I51.

"rake the attend- I52 is less than a full step,

the holding pawl I53 may not fall ini but merehe next ratchet tooth ofthis e spring I 54 will cause backi it is checked by the holdthe toothof the ratchet on which it was previously seated; During such retractionof the wheel is moved backward I52, the stepping pawl I51 in preparationfor 'a new scribed the pin 44 engages the long tooth I64 ping dog I29 sothat the clutch 46-48 is reendog again engages the pawl revolution ofthe rounds gaged, causing the member 41 and gear 41 to rotate with theshaft I1 and causing a quarter disk 4I. Thereupon if the currentcond'tions are such thatthe skipping dog I29 remains in the sameposition, the 48, the-clutch 49-48 is opened, and for two successiveadditional rounds the member 41 is stepped along by engagementof thestepping pawl I51 with the toothed portion thereof. At the end of thesecond succeeding round the skipping dog and pawl are again disengaged,the clutch 46-49 is again closed, and the measuring disk makes anotherquarter turn. The same sequence of operations may be repeated at the endof two more rounds so that the measuring disk 4| completes its finalquarter revolution, whereupon the arm 39 reenters the notch 42, thuscausing the dog 40 to be carried into the path of the pin 44 to therebyterminate the operation of the mechanism. 9

Whenever the mechanismis brought to rest under any of the variouscircumstances herein described, through the stop dog 40 being moved intothe path of the pin 44, the accompanying clockwise movement of the plate31 in carrying the arm 39 into the notch 42, correspondingly swings thearm I62 so as to changethe relationship between the angled extremity I63of said arm and the aperture I6I in the body of the pawl I53, from thatshown in Fig. 18 to that shown in.

Fig. 19, andthereby causes said pawl I53 to swing away from the ratchetI52. Said ratchet will thereupon be rotated counterclockwise, by itsspring I54, until it is restored to its normal position where its longtooth I54 engages the intermediate tooth I56 of said pawl I53.

It is evident that the signaling apparatus may transmit three rounds ofthe signal through the pulsating contact assembly PC, if the roundsmeasuring disk has been moved one-quarter of stored in the a revolutionbefore transmittal of signals through this assembly is permitted; If therounds wheel or'disk has moved one-half a revolution before thetransmitter receives possession of the line, two rounds of the signalwill be transmitted, and if the disk has moved three-quarters of arevolution, only one round will be transmitted. Accordingly, thisarrangement results in the repetition of the signal for a smaller numberof times after a determined period of delay, the number of repetitionsbeing reduced as the period of delay-is prolonged until but-a singleround of the signal may be transmitted, and ultimately-the mechanism maybe conditioned so that the signal will not be sent at all, but thesignal train will stop to conserve some of the potential energy mainspring I for a subsequent operation.

' Ordinary operation circuit is in normal condition and no othertransmitter associated with that circuit is in opera-. tion, theapparatus will operate in the normal.

immediate transmittal of the signal. Pulling of the handle 33 swings themaster plate 31, in a clockwise direction, removing the stop arm 39 fromthe notch 42 in the rounds disk 41 and snapping the stopdog 40 out ofthe move the stop dog path of the stop and stepping pin 44 on gear I9(Fig. .11). Movement of the plate 31 also disengages the contacts ofswitch ON and removes the pin 91 from the tailpiece 95 of the sendingarm 93, as well as swinging the angle I24 at the end of latch restoringlever I22 to the left, away from the depending end of pawl I08. As soonas the-stop dog 40 is removed from the pin 44, and the arm 39 isretracted from notch M, the signal train starts turning, due to therelease of energy from main spring I. The shunt connection provided bymember 8| with its contacts 82 and 83 is disconnected by opening theswitch ON so that current flows through the contacts of the pulsatingcontact assembly PC, the arms H, 12, and the connections 94 and 81,whereby magnet MM is energized. Armature 88 is thus immediately 68 assoon as its tailpiece was released from engagement with the pin 91. Theenergization of magnet MM raises the arm I02 so that the guard pin I06may pass under the end of this arm. When the shaft I1 starts rotatingfrom its normal position, the cam II3 moves out of supporting engagementwith the fluke I21 carried by latch lever or guard I09, so that thelower end of pawl I08 may engage the ledge I01 of armature lever I03,which has been moved by energization of magnet MM into the properposition to receive the lower end of the pawl. Thus the rightpath, andthe energization of the armature holding the arm I02 above its-path. Assoon as the fluke 93 leaves the skirt I00, it may engage the peripheryof the signal wheel, opening the contacts of switch assembly PC so thatthe magnet .is no longer energized. However, under these 08 ismechanically held conditions, the armature in its portative position,due to the end of lever I02.resting on pin I05. As one of the teeth 30moves the arm 9| to its switch closing position, the contacts ofassembly PC are again momentarily closed to energize the magnet MM topermit the armature to be electrically retained in portative positionbefore its mechanical support provided by the parts I02 and I06 becomesinoperative. Thus the electric pulsations are sent over the line orelectrical loop provided by conductors B and H, so that the signaldevices A and J in the main station may be'energized to indicate and/orrecord the signal being transmitted.

The skipping dog I29 is held out of the path of pawl 48, due to theposition of latch lever I09, so that the clutch 46-49 remains in itsclosed condition. Accordingly the gear 41 rotates with shaft I1, so thatthe rounds disk makes one revolution in four-revolutions of the shaft I1and the signal wheel. Accordingly four rounds of the signal aretransmitted before the notch 42 again receives the stop arm 39, thuspermitting the plate 31 to return to its normal position and to 40 intoengagement with the pin 44 (Fig. 10).

switch ON is closed, the stud 91 reengages tailhand end of arm I09 islocked in its depressed Simultaneously the shunt piece 95, and theprojection I24 at the end of arm I22 swings against the lower portion ofpawl I00 positively to return the latter to its inoperative position.

Due to the ratio of gears 1 and I6, the shaft I1 .Operaflon whentransmitters are four in interfering relatimzship its portativeposition, so that the ledge I01 on the arm I03 will engage the lower endof pawl I08 and thereby prevent the ledge I I8 from being carried bysaid pawl into is If, however, the, magat a time when the dog I I4 H3 asjust described, upon the path of the angle I I1 while the dog I in itselevated position. net MM is deenergized member H4, first step of itsmovement.

During-the beginning of each successive round of the signal wheel andsender arm .9I to move to the left unless otherwise prevented. At suchtimes, however, the fluke 93 engages the edge of skirt I 00, thuspreventing such a movement of the arm and p session by othertransmitters,- or if pulsations in current similar to busy signals causemomentary energization of magnet MM. For example, the shaft Thus, asdescribed above, after one or substantially one revolution of the shaftII, the pawl 4 may engage the skipping dog I 29, which is engaged, theclutch 4 648 is opened and member 41 with its pinion 41, the gear 5|meshed therewith, and the rounds disk 4| may remain stationary, althoughthe signal train continues its movement. However, each rotation of thegear I9 causes the pin 44 to engradual movement action of retractil'earm I32 carried end of said pawl ter of a revolution,

such position in the path of the lower end of pawl I08, engaged by saidpawl to thereby support latch arm I09 in its elevated position aftersaid am has thereafter been next raised by the action of cam II3, sothat the right-hand end of said arm will be moved downwardly to aposition where it will no longer be disposed in the pathof pin I06 andrestraint will be terminated. I09 will also carry I33 moving therewithinto engagement Such movement of said arm the sloping extension or flukewith the thereby move the the path of the pawl may then be closed, walloperate in the as the occurrence just described takes place when thenotch 45 in'the disk 46 has just passed beyond the free end of the pawl48, the closing of the clutch 48-48 will not become efiective until thesignal wheel I8 has thereafter completed nearly a full revolution, roundof the signal. After this, but three additional rounds will be sent fromthe transmitter, since the disk 4I had already made a quarter of arevolution at the time the skipping dog I29 was positioned to permitclosing of the clutch 46-48, and since no more than one round is sentout to each quarter revolution of the disk.

If the line should still remain busy, the counting ratchet wheel I52will continue its tooth-bytooth movement until the long tooth I64 isengageable with the pin 44, which throws the hooked or raking ratchetI52 into engagement with the toothed field I12 on the disk 41 (Figs. 4and 18), thus member 41, the parts being so proportioned that the wheelI52 is advanced less than a movement corresponding to a single one ofits ordinary teeth, so that the ratchet element I53 permits a slightbackward movement of the wheel I52 under the action of spring I54. Inthe course of the next revolution again engages t e 48, so that theclutch 46-48 whereupon the mechanism hooked ratchet I51 again to engagethe toothed,

field I12, thus moving the disk 41 far enough to disengage the pawl-48from the skippin dog I20, permitting when the notch 45 is next presentedto the free 48 near the conclusion of the next revolution of the gearI9, the member 41 with its gear 41 ,will be caused to rotate for onerevolution, thus turning the measuring disk M for a quarter Thereafter,if

session of by may be sent by the signal wheel after the notch 45 ispresented to the free end of said pawl.48, since the measuring disk hasmade one-half a revolution. .11, however, the line remains busy,'

I51 therewith, whereupon 48-48 is again closed and the disk 4I turnsanother quarso that thereafter but a of movement of the arm SI normalmanner. Inasmuch and has thus sent a.

clutch 46-40 to close, so that single signal round will be given if theline is released to the transmitter. After two more rounds, which resultin another closing of the clutch 48-48, the shaft I1 enters its finalround, the disk 4| passes through its final quarter revolution, and thenthe notch 42 is again presented to arm 30. The transmitter may gainpossession of the line to send a signal until the cam II3 leaves thefluke I21 of arm I08 at the beginning of this final round, correspondingto the final quarter revolution of the disk 4|.

The arrangement just described will also be effective to preventinterference between two transmitters should both transmitters beoperated at the same time or, in effect, simultaneously. Under theseconditions the sender contacts PC of both transmitters may at firstoperate in synchronism, as in any case of normal operation. If, forexample, the two transmitters have signals presenting similar digits,when the initial teeth of the wheels I8 0! the respective transmittersare withdrawn from their respective fiukes 93, both transmitters may atfirst op- .erate in synchronism. For example, assume that onetransmitter sends signal pulsations according to the formula 2-3-5, andassume that the other transmitter sends a signal 2-2-5;

' may operate together until upon the line will mitter sending thesignal longer than the interval between consecutive strokes of anynumeral, so that the movement Emergency operation V when there is abreak in thelinecircuit so that current may not be received by themagnet MM even momentarily, as, would be the case where the line under abusy condition, the mechanism automatically operates to close anemergency line which normally may be in the form of a connection to acommon return conductor, such as the ground. when the box is pulledunder these conditions, the initial position of the parts may be thesame as described above in connection with a busy test or when boxes arein interfering relation. The skirt I00 is in blocking relationship tothe fluke 03, thus preventing the movement of the arm 8I to a positionwhere the contacts of assembly PC will open.

the shaft I1 starts rotation, the cam II8 leaves the fluke I21 0! thelatch arm I00, mitting the latter to rock counterclockwise under theaction of spring I28, so that the end of arm I09 is disposed in blockingrelation to guard pin I06 to prevent movement of sender arm 9| when theskirt I00 passes out of engagement with (Fig. 13). The cam II3 underthese conditions is effective in lifting the ground switch actuator II4to a position where the projection the second circuit is Thereupon the I1 thereof is latched over the ledge H8 upon the left-hand line section Hbetween the boxes E and pawl-108, the projection I24 of restoring armI22 F, the emergency switch ES having been closed When the cam H 3 hassubstantially completed of the battery CB while transferring thetermione revolution, during which the clutch .46-48 ha] of the linesection H to the right-hand termihas been disengaged, the skirt I00 issupporting ha] of the battery. Under these conditions curfluke 93, andcam H3 engages the fluke I21 of rent may flow from the right-handterminal of the latch-lever I09, rocking the latter clockwise, thebattery through the lead B, conductors 62, so that the switch actuatorH4, which is now 61, 13, 18, 11 and 58, to the common return or ari linecurrent), w l be fted o a p s t on effective in actuating thesignal-responsive dewhere it engages the lever I31, lifting the lattervice A against the tension spring H5 so that the switch emergency switchES permitting the pulsing into m may sw n ab u its piv t 43 to movwhichever one of the two line connections may con a tor. 8 into e a m ntwith nta ts be closed, or, if both are closed, pulsing into them 5 and hs cl sing the ground or emergency simultaneously. Obviously if the linebreak had it he lifting o latch also moves d occurred at point Y (Fig.21) rather than at point 9 away rom pawl 48 (Fi 4), so hat clutch x, theoperation of the transmitter through its 45-48 is reengaged and roundsdisk 4| starts ground switch ES would be similar to that just tati wh nthe n t h 45 has a ain e n p described, the receiving device J ratherthan the sented to the free end of said pawl 48. device A beingactuated.

Under these onditions t e inclined end of As a further example ofpossible faulty circuit member I31 has a cam-like e gagem With theconditions, let it be assumed for convenience of eyllndrieal pp t r theeon aot r 73, thus description that a short circuit is due to the actingas a prop to hold mature 8 n D joinder of ,point X with point Y of theline seet v Position g l), the armatu e being tion B and that it isdesired to signal from the moved and h d by projection on armintermediate box E and, furthermore, that the gaging h m r p n Furtherswitch EW has been moved to its alternate position of the cam 3 Willthereupon withdraw 1t tion for emergency working (Fig, 23) When the fromengagement with the fluke I21, thus p rswitch ES closes under theseconditions, one side lnitting m [0 o m v responsive to the \of the linewill be provided by the ground conspring until t lower end of the lnection or common return CR, while the opposite thus preventing movementof said lever to posit rs B and H in parallel.

tion where its free end would be disposed in the If th r is an opencircuit, for example, at the path of pin I05 and final y Clearing the Pof left of point X on the line loop, and if the sevmovement of said pin;t f end o armature ered end of the line which extends to the right of pojecti n 39 mov it m I31. Thus tion' of their emergency switches ES; inother when the skirt I00 passe o of engagement t -words, performing asif the circuit was completed the fluke 93, the-sender 9| is free to moveto its through it or al path, except in that the recircuit openingposition and may oscillate sultant signal will be manifested onlybyreceivresponse to the Co our of the Wheel intering device A. The boxesatthe other side of the mittently closing the contacts of assembly PC inbreak namely boxes F and h ill response to eng g m nt w the teeth 301115quire the closing of their' respective emergency tribnt d p h Wheelhmovement of switches ES to apply a ground connection, wherearm I09caused its slopin extension I33 to act by the left-hand circuit may beclosed and sigagainst he al'ln carried by the Skipping naling effect maybe manifested on the receiving I29 to s ing id o toitsinoperative'oosition device J. If, for example, there should becirand thereby permit closure of the clutch -48, t openings t 5 t tpoints X and Y th whic closure becomes efieetive when the notch box Ewould become isolated and in a hopeless 45 is then ne t Presented to thefree d of the condition. However, the remaining boxes G F paw 48following Substantially revolution (if-the D and C could still operateafter their emergency signal wheel '8, SO that the rounds dlSk I will orgrounding switches had been automatically thereafter Comp e the finalthree-fourths of its closed. Under these conditions, if an attempt isrevolution while the emergency Switch is made to operate its box E, theemergency switch closed, and t e contacts of assembly PC will act willbe closed at the end of the first revolution of to formulate four signalrounds, the formulation thesignal wheel 3 and t movement of th of one ofwhich will occur prior to the presenta- 9 permitted, during t fucceeding tion of notch 5 o p w 8 as just expla drounds of the signalwheel will not cause response The emergency Switching arrangement ofeither instrument A or J. Since, however, the fective t permit propertransmittal of the ig-, clutch 46-40 has remained closed, the rounds nalunder many malconditionsof the line, a few disk 4 t t continually duringt five revo of which will be pointed out to S w the general lutions ofthe shaft l1 and wheel l8, so that it utility of this switchingarrangement. For ex-' is returned-to a position where the notch 42reample, referring to Fig. 21, let it be assumed that ceives the stoparm 39 while the stop 40 simultathere hasbeen a line break at the pointX in the neously engages the'pln 44. Accordingly under 75' sponse ofeither mally positioned, such grounding will not alter theresponsiveness of devices A and J to signals from any of the boxes, evenif of low resistance. If, during the effectiveness of such a lowresistance ground of the external circuit, the central oflice switch EWis positioned as shown in Fig. 23, signals from-boxes to the right ofsuch ground connection will be responded to by device A and those fromboxes to the left of such ground will be responded to by device J; sothat, if such ground connection developed atX, device A would respond toboxes C, D and E and device J would respond to boxes F and G.

Should low resistance ground connections develop at two or more points,or should a low resistance ground connection develop at one point and abreak occur at another point, signals from any box or boxes situated inthe circuit between such defects would fail to cause redevice A or J.For example, should the circuit be grounded at X and at Y or broken at Xand grounded at Y, or vice versa, any one of such conditions wouldrender the devices A and J unresponsive to box E, irrespective of thepositioning of central office switch EW.

The arrangement of emergency switch ES permits shunting or excluding themagnet M from the circuitso that a break in the magnet winding or in theimmediate electric connections or the like does not prevent emergencyworking of the transmitter. Furthermore, this arrangement also isadvantageous, since it requires relatively less current, sinceenergization of the magnet is not required when working under emergencyconditions, thus permitting operation with a weak current.

Operation with optional circuit arrangement Fig. 22.shows a typical typeof circuit which may be employed rather than that shown in Fig. 21, thedifferences in the circuits being in the arrangement of the centralstation portion CS. In the circuit arrangement shown in Fig. 22, whichforms a portion of the subject matter of my copending application SerialNo. 573,151, filed on even date herewith, the leads H and B correspondto those shown in Fig. 21 and may be connected to the signal boxes inexactly the same manner. The left-hand or primary winding of atransformer T may be connected to any suitable current source (notshown) which, for example, may be the commercial city lines, while thesecondary winding of transformer T is connected across the inputdiagonal of a rectifier bridge or network RN. The latter comprises fourrectifier units U, V, W and Z, so that one-half wave of a current cyclemay cause the upper terminal of the secondary winding of transformer Tto be positive and the current may. flow through rectifier unit W,receiving device A, lead B, serially connected boxes C, D, E, F and G,lead H, re-

.ceiving device J, and rectifier V to the lower terminal of thesecondary winding. During the next half cycle the lower terminal windingof transformer T may be positive, so that the current may flow outwardfrom rectifier unit Z, thence over the same loop to return overrectifier unit U. Thus each half-cycle of the alternating current supplymay be rectified in the network RN to provide a uni-directionalpulsating current for the line loop and the devices therein rather thanthe direct current source CB of Fig. 21. I.

The central station CS, when having an arrangement such as shown in Fig.22, requires no special switching or circuit changes for emergencyworking. For example, it may be assumed that an opening in the linesection H has occurred at a point X, such as shown in Fig. 21, and thatsubsequently the box E has been pulled. After one round of the signalwheel the emergency switch of the box is closed in the same manner asalready described, so that during one-half cycle of the alternatingcurren current may flow from the lower terminal of transformer T throughthe rectifier unit Z, the serially connected device A, and stations inthe line section B to the active signal initiating station, thencethrough the pulsing contact assembly PC of that station and its switchES to the ground or return CR, whence the current will be received overthe manifesting device R in the central station CS, thereupon passing tothe upper terminal of the secondary winding. f the transformer. Duringthe next half cycle the direction of electromotive force will be such asto urge current flow toward the upper terminal of the transformersecondary winding T, from which parallel paths to the active stationwill be provided through manifesting device R and the ground or returnCR, and through rectifier unit W, device A and line section B; but noreturn path will be provided from the active station to the lowerterminal of the transformer secondary winding.

As another example of the emergency working of the arrangement shown inFig. 22, in combination with boxes of the type disclosed herein, let itbe assumed that the line loop sections B and H are connected by contactof points X and Y at either side of the transmitter E, thusshortcircuiting this transmitter. Under these conditions when the upperterminal of the, transformer T is positive, current may flow therefromthrough the rectifier W, line section B into the line section H andthence return through the rectifier unit V to the opposite terminal ofthe transformer, while current may also flow throughthe device R,emergency conductor CR, switch ES of box E, and thence through conductorH and unit V. When the lower terminal of the transformer T is positivecurrent may flow through the unit Z, the line section B, to thecontacting point of X and Y, a portion of the current then flowingthrough the leads 62 and G4, the contact members I3 and 14, to theemergency switch ES and thence through the lead 11 to the common returnCR from which the device R may receive the signals, the current thenpassing to the upper or negat've terminal of the transformer. It is thusevident that under these conditions the signal device R will be actuatedby alternating current impulses received from the signal box E. i

Obviously the wiring diagram shown inFig. 22 is but a typical example ofa circuit arrangement which may be used advantageously with a signal boxconstructed in accordance with the present invention; in fact, it shouldbe understood

